Patient-Controlled Analgesia

“How’s a person supposed to get any sleep if he has to stay up all night pressing the button?” a patient asked in a 2003 editorial.1 Nurses know patient-controlled analgesia (PCA) can be a wonderful tool for managing pain, but this mode of pain control involves careful patient selection, appropriate dosing and patient education to ensure patient safety.

At the press of a button, PCA allows the patient to manage their own pain by delivering an IV analgesic dose within preset parameters. The pump delivers, typically, an intravenous narcotic analgesic dose. Theoretically, when the patient becomes sedated, he stops pushing the button. In combination with individualized prescriptions for pain management, this built-in safety feature helps prevent respiratory depression.

The healthcare practitioner orders the type of medication, demand dose, the bolus or extra dose and lockout interval. Typical dose intervals allow self-administration of a dose of medication every 6-8 minutes or until the first dose had time to exert its effect.2 Another lockout interval is set for 1-4 hours, the total amount the patient may receive in that time period.

Once a patient has self-administered the dose(s) allotted for the time period, the pump will not deliver another dose, even if the patient keeps pushing the button. While basal doses are falling out of favor, this continuous infusion rate may be ordered. If breakthrough pain occurs, the patient presses the button to receive additional medication.

Advantages & DisadvantagesResearch shows PCA is superior to intermittent injection of pain medication, even by the IV route.3 Patients use less narcotic, do not have to wait for the nurse to bring the medication, and have greater overall satisfaction with better analgesia and lower pain scores than patients who request analgesia from the nursing staff.4 By controlling pain, patients can move more readily, take deep breaths and ambulate earlier, reducing the risk of post-operative complications.2

PCA involves patients in their own care, giving them control and ultimately rendering better patient outcomes. Patients do not experience the peaks and valleys of intermittent opioid use as the patient can maintain a steady serum level. Patients are better able to prevent undesirable side effects such as sedation, nausea, vomiting and hallucinations because they tend to self-administer sufficient — but not excessive — analgesic doses.5

This active patient participation is regarded by healthcare professionals as an important contribution toward the patients well-being which promotes recovery and earlier discharge.2,5

Nurses cited additional advantages to PCA use, including reduced nursing workload, improved pain relief and decreased anxiety.5 However, King and Walsh also cite a study where PCA allows nurses to distance themselves from patients in pain. In addition, some patients felt the nurse spent less time with them.

The lesson: PCA is a process, not a machine.6 The time saved accessing intermittent analgesia can be spent assessing and teaching about pain management. The preadmission and preoperative holding areas are important points in perioperative care to teach patients how to use the PCA pump and use a pain intensity rating scale, critical to the success of post-operative pain management.

Candidates for PCA

The ideal candidate for PCA must be able to follow instructions and be physically able to push the button independently. The safety feature of PCA is bypassed when another individual, nurse or family member pushes the button for pain relief because they perceive the patient is uncomfortable. PCA by proxy, as this is known, constitutes a dangerous practice because the safety feature of not being able to press the button when oversedated is bypassed. Marderscites such an instance when the patient asked the nurse to push the button; the patient became unresponsive and died.7 Another such complication cited regarded an 18-year-old who requiredmechanical ventilation after a family member gave a morphine dose believing it was the call bell.8 The Joint Commission and the Institute for Safe Medication Practices (ISMP) recommend PCA by proxy be eliminated and that education to patients and families emphasize that only the patient should push the button.6

PCA errors can be classified into two categories: human error and equipment error or malfunction. Data from the FDA’s Manufacturer and User Facility Device Experience (MAUDE) indicate that 6.5 percent were due to operator error, the majority of which were programming errors.6,9. An additional 76.4 percent were due to device malfunction. The Joint Commission also reported that of 460 serious PCA errors, 15 were related to PCA by proxy; 12 by family members, 2 by nurses and 1 by the pharmacist.10

Poor candidates for PCA include infants and very young children, confused adults or those who cannot follow instructions, such as people with significant developmental delays or those who are unconscious. Patients who are obese or asthmatic, or those taking drugs that potentiate opiates, such as sedatives or hypnotics, muscle relaxants and antiemetics, should not use PCA. Patients with sleep apnea should not use PCA and the nurse should screen all patients for sleep apnea before initiation.6

Substance abusers also are not good candidates, as pain may be hard to distinguish from drug cravings and the ability to receive medication on demand may reinforce the drug-seeking “habit.” This latter group benefits from long-acting medications whether oral or transdermal.

Pharmacologic Management

Medications commonly used for intravenous PCA include hydromorphone (Dilaudid), morphine and fentanyl (Sublimaze). It is important the nurse recognizes, milligram per milligram, these drugs are not equivalent. Morphine, the standard to which all medications compare, is less potent than hydromorphone or fentanyl. Genetics may play a role in response to a specific opiate; thus, the nurse should focus on assessing patient response and intervening based on individual reports of pain.6

Morphine is one of the most commonly used opiates due to its easy titration and multiple routes of administration. It is the first-line agent recommended by the Society of Critical Care Medicine and is the gold standard for both acute and chronic pain management.11 Morphine may accumulate in patients with compromised renal function prolonging sedation and respiratory depression.

Hydromorphone is a semi-synthetic narcotic that is six times more potent than morphine. It produces more sedation with less euphoria than equianalgesic (producing the same degree of analgesia as) doses of morphine. It may cause less respiratory depression and physical dependence than morphine. It also may cause transient hyperglycemia. It is ideal for use in patient with renal impairment because it causes no metabolite buildup.12

Fentanyl (Sublimaze) is a synthetic opioid. Milligram for milligram, it is 100 times more potent than morphine and has a more rapid onset of effect and recovery than morphine or hydromophone; but it may cause a prolonged effect in critically ill patients when used repeatedly or in large doses.12 Fentanyl does not cause histamine release and is preferred over morphine when hypotension is a concern.

Based on potential dosing errors and potency, use of Fentanyl is recommended for use only in intensive care and post-anesthesia care units or by pain management specialists (see Tables 1 & 2).13

PCA by the epidural route (PCEA) is used for regional pain management to provide pain relief with less systemic side effects. Local anesthetics such as bupivacaine or ropivacaine with or without morphine may be used. The medication is diffused across the dura and subarachnoid spaces, circulating in the CSF to the opiate receptors in the brain and spinal cord.12

Epidural analgesia causes less sedation and may cause less nausea. Side effects include hypotension and motor deficits. For patient safety, epidural catheters should be clearly marked and injection ports taped over to prevent accidental injection of other medications. Contraindications to epidural analgesia include thrombocytopenia, coagulapathy or use of anticoagulants.

The single most significant source of harm is inadvertent injection of a medication containing preservatives. This is the rationale for using different port-free tubing than is used for IV PCA infusions. Also, the effects for which patient monitoring is necessary vary according to whether the epidural infusion contains more “-caines” agents (that is, more motor side effects) than opioids.

PCA Safety

The ISMP has cited instances of dangerous errors that can provide nurses with insight. Harmful events affected the elderly more than other age groups.10,13

Equipment-related issues, such as incorrect programming of PCA units, also were implicated. Common errors include programming errors where “milliliters” was confused with “mg” or “mgs” was confused with “mcgs”; the loading dose was confused with the basal or bolus dose; or the concentration was set incorrectly, resulting in overdose of medication.

Recommendations for safer PCA use include using standard concentrations, using the same pump throughout the institution, requiring two nurses to verify the order against the pump when initiating PCA or making changes, and verifying the IV line where the medication is infusing. The pump should prohibit free flow of medication. ISMP suggests agencies consider restricting fentanyl use to anesthesia, critical care areas or the pain management team.

The nurse should monitor the patient closely and frequently to assess pain and sedation levels at least every 2 hours, especially within the first 24 hours and at night, when hypoventilation and nocturnal hypoxemia may occur. Avoid basal doses in opiate-naïve patients, meaning patients who have received opiates for fewer than 7 days.

As always, nurses should have input into choosing PCA pumps.

Inadequate Analgesia

The nurse should assess for comfort using standard numeric or behavior scales every 1-2 hours and evaluate the number of demands the patient has made for medication. If inadequate analgesia is reported or the demand for pain medication is excessive, the physician may order rescue or breakthrough doses, extra doses of medication that the nurse can administer to manage increased pain. The nurse can still see how many demands a patient makes for analgesia, which assists in further assessing discomfort.

If the patient attempts to activate the PCA two times more than the doses delivered, the nurse should request an order for a dosage increase or a shortened dosing interval.2 While pain assessment is important, excessively pushing the button may signal confusion where the patient is and trying to call the nurse and not attempting to activate the pump.

Essentially, the amount of drug the patient uses in an hour needs to make sense to the nurse. If the patient can have 8 mg of morphine per hour, only uses 6 mg and reports a low pain score, the plan of care is working. If the patient can have 8 mg of morphine per hour, but is pushing the button every 2 minutes and reports a pain scale of 10, it’s probably not working.

Other reasons for inadequate analgesia include mechanical pump failures and IV infiltration. It can take as long as 1-2 hours to get an IV restarted, leaving the patient without pain relief. If this occurs, request the physician to order the medication by a different route temporarily.

A patent IV with fluids infusing is necessary to deliver the medication to the vein. If IV fluids have been discontinued because the patient is able to eat, the nurse must maintain a low rate or KVO infusion for PCA is to be carried from pump into the patient’s vein. Standard order sets for PCA can prevent lapses in analgesia such as these and provide direction for side effects such as respiratory depression, nausea or vomiting, or itching.

Insufficient analgesia in the opiate tolerant may include such withdrawal symptoms as diarrhea, vomiting, anxiety runny nose, yawning, goosebumps and tearing. When these symptoms are present, the nurse should collaborate with the provider to increase the opiate dose.

Respiratory Depression

Even opiate tolerant patients can become oversedated with high enough doses. Respiratory depression occurs at a rate of 0.19-5.2 percent.6,9 Sedation precedes opiate-induced respiratory depression. Therefore, sedation level should be regularly assessed with a standard sedation scale.9 The nurse should note the rate of respiratory depression is much less than the 10 percent of patients who experience under treatment of their pain.2, 9

Risks for respiratory depression include age greater than 70 years, using a basal dose infusion, renal hepatic, pulmonary or cardiac impairment, sleep apnea, concurrent administration of CNS depressants, upper abdominal or thoracic surgery, or bolus doses over 1 mg. They point out that the rate of respiratory depression is much less than the 10 percent of patients who experience under treatment of their pain.2,9 More frequent monitoring during the night, is recommended to further decrease respiratory complications in at risk individuals.6

Sedation

Symptoms of over-sedation include decreased level of consciousness and hypoventilation measured by end-tidal CO2, with hypoxemia or blood CO2 level >45 mmHg. When sedation is characterized by drifting off during conversations the nurse should plan to decrease the opioid dose and stop the basal infusion if used. Monitor the sedation level every 15 minutes.

If the patient is somnolent with minimal or no response to shaking or loud stimulation, the provider must be notified immediately. Standing orders describing expected nursing actions should be incorporated into the PCA order sets. A narcotic antagonist, naloxone (Narcan), is indicated.12 PCA order sets that address these issues will allow for timely interventions.9

If the patient is sedated but complaining of pain and an increase in opiate dose is contraindicated, suggest a non-steroidal anti-inflammatory drug such as ketorolac (Toradol) to enhance the analgesic effect. The American Pain Society recommends all patients receiving opioids also receive adjunct pain therapies unless there is a contraindication. Adding an additional narcotic is not recommended due to risk of respiratory depression.

The unit should always have naloxone on hand for patients receiving PCA. When using naloxone, recognize that pain will return abruptly. That pain may be more severe than previous and more difficult to control. Use the smallest dose of naloxone to reverse respiratory depression. Keep in mind the duration of naloxone will be shorter than the narcotic; naloxone may need to be repeated several times.

The healthcare team must outweigh the risk of respiratory depression over the physiologic implications of return in pain. Side effects of naloxone are related to the abrupt reversal of opioids resulting in sympathetic stimulation including nausea, vomiting, sweating, hypertension, tachycardia, ventricular irritability and pulmonary edema.12 Opioids may be resumed at a 50 percent reduction in dose when sedation level and respiratory status are stable.2

End-Tidal CO2 Monitoring

End-tidal CO2 monitoring is a safety feature used in conjunction with PCA to detect exhaled CO2, alerting the nurse to hypoventilation and risk for respiratory depression.

The patient should be taught this device is an important safeguard and should not be removed. Some agencies permit use of PCA without CO2 monitoring; others require a different method of pain management if the monitor is not worn.

Other Opioid Side Effects

Of course, the patient can still develop side effects of opiates, including nausea or vomiting, constipation, urinary retention, pruritus or postural hypotension, all of which will need appropriate nursing intervention.

Weaning

Changing from PCA to oral or PRN dosing can cause confusion and distress. It may take as long as 15 minutes between when the patient requests pain medication and the nurse brings it.6 Control of pain is no longer at the patient’s fingertips. The nurse’s role is to empower patients to understand the medication regimen and not overlook the importance of educating the patient to ask for the medication before performing an activity or procedure that might be painful.6

The nurse should anticipate weaning from pain medication will be systematic and slow, decreasing the dose from 25-50 percent every 24-48 hours. Using an equianalgesic dosing chart will help the weaning process. Switching from PCA to oral opioids involves calculating the opioid dose over 24 hours and determining the equianalgesic dose for the new order.

Nursing Interventions & Education

It is important to avoid playing catch-up when initiating PCA. Pain should be brought under control before PCA is initiated. This may require an initial or larger bolus dose. When patients with severe pain have low serum levels of opiates, it is difficult to regain control with the small doses given through the pump.4

Patients should be instructed not to wait until the pain becomes severe before pushing the button for a medication dose. This includes not becoming distracted by activities or visitors so that when the distraction ends, pain will return and he will need to “play catch up.”4 Patients should be assured the use of opiates rarely results in addiction (1-3 percent), and the benefits of proper pain management clearly outweigh the complication of immobility, hypercoagulability and activation of the stress response.

Many surgical patients do not receive teaching about the pump or use the pump until after surgery. The ideal time to educate patients and demonstrate the pump is preoperatively. If teaching is done with family members present-emphasize clearly that only the patient is to activate the pump to prevent dangerous overdose.

As always, nurses should include non-pharmacologic interventions for pain. Massage, repositioning, ice or heat can be used as adjuncts to pain management. Distraction may be useful; however, a patient in severe pain may be unable to concentrate on complex mental activities.4

Another Type of PCA

The fentanyl iontophoretic transdermal system (ITS), IONSYS, is a method of delivering narcotic analgesic through the skin. When the patient initiates a dose, an electrical current is activated, which moves the fentanyl from the drug reservoir through the skin and into the systemic circulation. Each activation of the system administer 40 mgc of fentanyl over 10 minutes; at the onset of administration the system beeps and during the administration period a red light comes on.14 Patients must be alert and able to control the device, which is not intended for home use.

Comparison of the efficacy and safety of fentanyl ITS with morphine PCA following gynecologic surgery found the two were therapeutically equivalent.15 Both patientsand nurses rated fentanyl ITS as more convenient and time efficient.14 Since infiltration is not a problem, theoretically, this may prove an advantage over the current system. As with all PCA, only the patient should activate this system.

Collaboration

Being aware of the ISMP and Joint Commission reports, nurses can collaborate with providers to ensure adequate analgesia is delivered in a safe fashion. Adhering to standards of care plus careful monitoring and assessment will ensure both pain control and patient safety.

Andrea Mann is an instructor at the ARIA Health School of Nursing, Philadelphia.

10. Institute for Safe Medication Practices. (2003, July 24). Part II: How to prevent errors; Safety issues with patient-controlled analgesia. Retrieved April 9, 2009 from the World Wide Web: http://ismp.org/newsletters/acutecare/articles/20030724.asp